Yemen's internationally backed president rejected a new United Nations peace proposal Saturday, as warplanes from the Saudi-led coalition backing him launched strikes that killed scores of rebels, civilians and prison inmates in the country's southwest.

Details of the latest peace proposal from U.N. special envoy Ismail Ould Cheikh Ahmed to President Abdu Rabu Mansour Hadi have not been officially disclosed.

But Reuters said they include provisions that would sideline Hadi and install a new government. The French news agency AFP reports Hadi refused to accept the proposal, which was delivered to him in the Saudi capital.

Meanwhile, witnesses say an air raid in the western city of Taiz killed at least 17 people in several residences where Houthi rebels are battling Saudi-backed government forces.

Hours later, witnesses said fresh airstrikes on a security headquarters at the rebel-controlled Red Sea port of Hodeida killed at least 40 people, including prisoners and security forces.

Details of that attack remained sketchy hours later. Medics confirmed the toll to the French news agency without estimating the number of wounded in the attack.

A Saudi-led coalition of regional Sunni governments has been attacking Houthis in Yemen in support of President Hadi since March of 2015. A U.N. report says the coalition airstrikes have killed nearly 4,000 people.

Houthi rebels, alleging years of discrimination by the Sana'a government, launched a rebellion in 2014 aimed at wresting power from President Hadi. Since then, more than 10,000 people, most of them civilians, have been killed.